The present invention relates to a variable displacement or capacity compressor, and more particularly to a variable displacement compressor suitable for use in an automotive vehicle.
In a conventional fluid machine, a mechanism for varying a displacement capacity is provided in a rotating member per se as shown in Japanese Unexamined Patent Publication No. 58-158382, for example. For this reason, a drive hub, a journal and the like are provided in an asymmetric relation with respect to a rotary shaft. Further, when the slant or inclination angle of a wobble plate is changed, the center of rotation of the journal is changed.
Since the rotating member of the conventional fluid machine is provided with the mechanism for varying the displacement capacity, there is caused an unbalance due to the rotation of the asymmetrically arranged components such as the drive hub and the journal. In order to cope with this, there is provided a balance weight or the like. With such structure, however, as the slant angle of the wobble plate varies, the center of rotation of the journal is displaced. Therefore, it is difficult to completely cancel or eliminate the unbalance. As a result, the unbalance becomes to be an eccentric load to increase noises and vibrations. This makes the user feel uncomfortable. In addition, the service life is shortened due to the mechanical vibrations.
U.S. Pat. No. 4,174,191 and U.S. Pat. No. 4,283,997 disclose a fluid machine in which a mechanism for varying the displacement capacity is provided in a rotating member per se as similar to the structure disclosed in the above-described Japanese Unexamined Pat. Publication No. 58-158382. Also in the structure of these U.S. Pats., it is necessary to consider keeping the balance of the rotating member.
U.S. Pat. No. 4,644,850 discloses a system in which a drive plate and a cylinder are rotated in synchronism with each other, but the system does not include a mechanism for slanting the drive plate.